linux/arch/sparc/include/asm/uaccess_32.h
Rusty Russell ad6561dffa module: trim exception table on init free.
It's theoretically possible that there are exception table entries
which point into the (freed) init text of modules.  These could cause
future problems if other modules get loaded into that memory and cause
an exception as we'd see the wrong fixup.  The only case I know of is
kvm-intel.ko (when CONFIG_CC_OPTIMIZE_FOR_SIZE=n).

Amerigo fixed this long-standing FIXME in the x86 version, but this
patch is more general.

This implements trim_init_extable(); most archs are simple since they
use the standard lib/extable.c sort code.  Alpha and IA64 use relative
addresses in their fixups, so thier trimming is a slight variation.

Sparc32 is unique; it doesn't seem to define ARCH_HAS_SORT_EXTABLE,
yet it defines its own sort_extable() which overrides the one in lib.
It doesn't sort, so we have to mark deleted entries instead of
actually trimming them.

Inspired-by: Amerigo Wang <amwang@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: linux-alpha@vger.kernel.org
Cc: sparclinux@vger.kernel.org
Cc: linux-ia64@vger.kernel.org
2009-06-12 21:47:04 +09:30

340 lines
11 KiB
C

/*
* uaccess.h: User space memore access functions.
*
* Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)
* Copyright (C) 1996,1997 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
*/
#ifndef _ASM_UACCESS_H
#define _ASM_UACCESS_H
#ifdef __KERNEL__
#include <linux/compiler.h>
#include <linux/sched.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <asm/vac-ops.h>
#endif
#ifndef __ASSEMBLY__
#define ARCH_HAS_SORT_EXTABLE
#define ARCH_HAS_SEARCH_EXTABLE
/* Sparc is not segmented, however we need to be able to fool access_ok()
* when doing system calls from kernel mode legitimately.
*
* "For historical reasons, these macros are grossly misnamed." -Linus
*/
#define KERNEL_DS ((mm_segment_t) { 0 })
#define USER_DS ((mm_segment_t) { -1 })
#define VERIFY_READ 0
#define VERIFY_WRITE 1
#define get_ds() (KERNEL_DS)
#define get_fs() (current->thread.current_ds)
#define set_fs(val) ((current->thread.current_ds) = (val))
#define segment_eq(a,b) ((a).seg == (b).seg)
/* We have there a nice not-mapped page at PAGE_OFFSET - PAGE_SIZE, so that this test
* can be fairly lightweight.
* No one can read/write anything from userland in the kernel space by setting
* large size and address near to PAGE_OFFSET - a fault will break his intentions.
*/
#define __user_ok(addr, size) ({ (void)(size); (addr) < STACK_TOP; })
#define __kernel_ok (segment_eq(get_fs(), KERNEL_DS))
#define __access_ok(addr,size) (__user_ok((addr) & get_fs().seg,(size)))
#define access_ok(type, addr, size) \
({ (void)(type); __access_ok((unsigned long)(addr), size); })
/*
* The exception table consists of pairs of addresses: the first is the
* address of an instruction that is allowed to fault, and the second is
* the address at which the program should continue. No registers are
* modified, so it is entirely up to the continuation code to figure out
* what to do.
*
* All the routines below use bits of fixup code that are out of line
* with the main instruction path. This means when everything is well,
* we don't even have to jump over them. Further, they do not intrude
* on our cache or tlb entries.
*
* There is a special way how to put a range of potentially faulting
* insns (like twenty ldd/std's with now intervening other instructions)
* You specify address of first in insn and 0 in fixup and in the next
* exception_table_entry you specify last potentially faulting insn + 1
* and in fixup the routine which should handle the fault.
* That fixup code will get
* (faulting_insn_address - first_insn_in_the_range_address)/4
* in %g2 (ie. index of the faulting instruction in the range).
*/
struct exception_table_entry
{
unsigned long insn, fixup;
};
/* Returns 0 if exception not found and fixup otherwise. */
extern unsigned long search_extables_range(unsigned long addr, unsigned long *g2);
extern void __ret_efault(void);
/* Uh, these should become the main single-value transfer routines..
* They automatically use the right size if we just have the right
* pointer type..
*
* This gets kind of ugly. We want to return _two_ values in "get_user()"
* and yet we don't want to do any pointers, because that is too much
* of a performance impact. Thus we have a few rather ugly macros here,
* and hide all the ugliness from the user.
*/
#define put_user(x,ptr) ({ \
unsigned long __pu_addr = (unsigned long)(ptr); \
__chk_user_ptr(ptr); \
__put_user_check((__typeof__(*(ptr)))(x),__pu_addr,sizeof(*(ptr))); })
#define get_user(x,ptr) ({ \
unsigned long __gu_addr = (unsigned long)(ptr); \
__chk_user_ptr(ptr); \
__get_user_check((x),__gu_addr,sizeof(*(ptr)),__typeof__(*(ptr))); })
/*
* The "__xxx" versions do not do address space checking, useful when
* doing multiple accesses to the same area (the user has to do the
* checks by hand with "access_ok()")
*/
#define __put_user(x,ptr) __put_user_nocheck((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))
#define __get_user(x,ptr) __get_user_nocheck((x),(ptr),sizeof(*(ptr)),__typeof__(*(ptr)))
struct __large_struct { unsigned long buf[100]; };
#define __m(x) ((struct __large_struct __user *)(x))
#define __put_user_check(x,addr,size) ({ \
register int __pu_ret; \
if (__access_ok(addr,size)) { \
switch (size) { \
case 1: __put_user_asm(x,b,addr,__pu_ret); break; \
case 2: __put_user_asm(x,h,addr,__pu_ret); break; \
case 4: __put_user_asm(x,,addr,__pu_ret); break; \
case 8: __put_user_asm(x,d,addr,__pu_ret); break; \
default: __pu_ret = __put_user_bad(); break; \
} } else { __pu_ret = -EFAULT; } __pu_ret; })
#define __put_user_nocheck(x,addr,size) ({ \
register int __pu_ret; \
switch (size) { \
case 1: __put_user_asm(x,b,addr,__pu_ret); break; \
case 2: __put_user_asm(x,h,addr,__pu_ret); break; \
case 4: __put_user_asm(x,,addr,__pu_ret); break; \
case 8: __put_user_asm(x,d,addr,__pu_ret); break; \
default: __pu_ret = __put_user_bad(); break; \
} __pu_ret; })
#define __put_user_asm(x,size,addr,ret) \
__asm__ __volatile__( \
"/* Put user asm, inline. */\n" \
"1:\t" "st"#size " %1, %2\n\t" \
"clr %0\n" \
"2:\n\n\t" \
".section .fixup,#alloc,#execinstr\n\t" \
".align 4\n" \
"3:\n\t" \
"b 2b\n\t" \
" mov %3, %0\n\t" \
".previous\n\n\t" \
".section __ex_table,#alloc\n\t" \
".align 4\n\t" \
".word 1b, 3b\n\t" \
".previous\n\n\t" \
: "=&r" (ret) : "r" (x), "m" (*__m(addr)), \
"i" (-EFAULT))
extern int __put_user_bad(void);
#define __get_user_check(x,addr,size,type) ({ \
register int __gu_ret; \
register unsigned long __gu_val; \
if (__access_ok(addr,size)) { \
switch (size) { \
case 1: __get_user_asm(__gu_val,ub,addr,__gu_ret); break; \
case 2: __get_user_asm(__gu_val,uh,addr,__gu_ret); break; \
case 4: __get_user_asm(__gu_val,,addr,__gu_ret); break; \
case 8: __get_user_asm(__gu_val,d,addr,__gu_ret); break; \
default: __gu_val = 0; __gu_ret = __get_user_bad(); break; \
} } else { __gu_val = 0; __gu_ret = -EFAULT; } x = (type) __gu_val; __gu_ret; })
#define __get_user_check_ret(x,addr,size,type,retval) ({ \
register unsigned long __gu_val __asm__ ("l1"); \
if (__access_ok(addr,size)) { \
switch (size) { \
case 1: __get_user_asm_ret(__gu_val,ub,addr,retval); break; \
case 2: __get_user_asm_ret(__gu_val,uh,addr,retval); break; \
case 4: __get_user_asm_ret(__gu_val,,addr,retval); break; \
case 8: __get_user_asm_ret(__gu_val,d,addr,retval); break; \
default: if (__get_user_bad()) return retval; \
} x = (type) __gu_val; } else return retval; })
#define __get_user_nocheck(x,addr,size,type) ({ \
register int __gu_ret; \
register unsigned long __gu_val; \
switch (size) { \
case 1: __get_user_asm(__gu_val,ub,addr,__gu_ret); break; \
case 2: __get_user_asm(__gu_val,uh,addr,__gu_ret); break; \
case 4: __get_user_asm(__gu_val,,addr,__gu_ret); break; \
case 8: __get_user_asm(__gu_val,d,addr,__gu_ret); break; \
default: __gu_val = 0; __gu_ret = __get_user_bad(); break; \
} x = (type) __gu_val; __gu_ret; })
#define __get_user_nocheck_ret(x,addr,size,type,retval) ({ \
register unsigned long __gu_val __asm__ ("l1"); \
switch (size) { \
case 1: __get_user_asm_ret(__gu_val,ub,addr,retval); break; \
case 2: __get_user_asm_ret(__gu_val,uh,addr,retval); break; \
case 4: __get_user_asm_ret(__gu_val,,addr,retval); break; \
case 8: __get_user_asm_ret(__gu_val,d,addr,retval); break; \
default: if (__get_user_bad()) return retval; \
} x = (type) __gu_val; })
#define __get_user_asm(x,size,addr,ret) \
__asm__ __volatile__( \
"/* Get user asm, inline. */\n" \
"1:\t" "ld"#size " %2, %1\n\t" \
"clr %0\n" \
"2:\n\n\t" \
".section .fixup,#alloc,#execinstr\n\t" \
".align 4\n" \
"3:\n\t" \
"clr %1\n\t" \
"b 2b\n\t" \
" mov %3, %0\n\n\t" \
".previous\n\t" \
".section __ex_table,#alloc\n\t" \
".align 4\n\t" \
".word 1b, 3b\n\n\t" \
".previous\n\t" \
: "=&r" (ret), "=&r" (x) : "m" (*__m(addr)), \
"i" (-EFAULT))
#define __get_user_asm_ret(x,size,addr,retval) \
if (__builtin_constant_p(retval) && retval == -EFAULT) \
__asm__ __volatile__( \
"/* Get user asm ret, inline. */\n" \
"1:\t" "ld"#size " %1, %0\n\n\t" \
".section __ex_table,#alloc\n\t" \
".align 4\n\t" \
".word 1b,__ret_efault\n\n\t" \
".previous\n\t" \
: "=&r" (x) : "m" (*__m(addr))); \
else \
__asm__ __volatile__( \
"/* Get user asm ret, inline. */\n" \
"1:\t" "ld"#size " %1, %0\n\n\t" \
".section .fixup,#alloc,#execinstr\n\t" \
".align 4\n" \
"3:\n\t" \
"ret\n\t" \
" restore %%g0, %2, %%o0\n\n\t" \
".previous\n\t" \
".section __ex_table,#alloc\n\t" \
".align 4\n\t" \
".word 1b, 3b\n\n\t" \
".previous\n\t" \
: "=&r" (x) : "m" (*__m(addr)), "i" (retval))
extern int __get_user_bad(void);
extern unsigned long __copy_user(void __user *to, const void __user *from, unsigned long size);
static inline unsigned long copy_to_user(void __user *to, const void *from, unsigned long n)
{
if (n && __access_ok((unsigned long) to, n))
return __copy_user(to, (__force void __user *) from, n);
else
return n;
}
static inline unsigned long __copy_to_user(void __user *to, const void *from, unsigned long n)
{
return __copy_user(to, (__force void __user *) from, n);
}
static inline unsigned long copy_from_user(void *to, const void __user *from, unsigned long n)
{
if (n && __access_ok((unsigned long) from, n))
return __copy_user((__force void __user *) to, from, n);
else
return n;
}
static inline unsigned long __copy_from_user(void *to, const void __user *from, unsigned long n)
{
return __copy_user((__force void __user *) to, from, n);
}
#define __copy_to_user_inatomic __copy_to_user
#define __copy_from_user_inatomic __copy_from_user
static inline unsigned long __clear_user(void __user *addr, unsigned long size)
{
unsigned long ret;
__asm__ __volatile__ (
".section __ex_table,#alloc\n\t"
".align 4\n\t"
".word 1f,3\n\t"
".previous\n\t"
"mov %2, %%o1\n"
"1:\n\t"
"call __bzero\n\t"
" mov %1, %%o0\n\t"
"mov %%o0, %0\n"
: "=r" (ret) : "r" (addr), "r" (size) :
"o0", "o1", "o2", "o3", "o4", "o5", "o7",
"g1", "g2", "g3", "g4", "g5", "g7", "cc");
return ret;
}
static inline unsigned long clear_user(void __user *addr, unsigned long n)
{
if (n && __access_ok((unsigned long) addr, n))
return __clear_user(addr, n);
else
return n;
}
extern long __strncpy_from_user(char *dest, const char __user *src, long count);
static inline long strncpy_from_user(char *dest, const char __user *src, long count)
{
if (__access_ok((unsigned long) src, count))
return __strncpy_from_user(dest, src, count);
else
return -EFAULT;
}
extern long __strlen_user(const char __user *);
extern long __strnlen_user(const char __user *, long len);
static inline long strlen_user(const char __user *str)
{
if (!access_ok(VERIFY_READ, str, 0))
return 0;
else
return __strlen_user(str);
}
static inline long strnlen_user(const char __user *str, long len)
{
if (!access_ok(VERIFY_READ, str, 0))
return 0;
else
return __strnlen_user(str, len);
}
#endif /* __ASSEMBLY__ */
#endif /* _ASM_UACCESS_H */